Electrical heating device



Feb. 11, 1941.

G. H. HOREY ELECTRICAL HEATING DEVICE Filed May 1, 1939 lnven'ror-Patented Feb. 11, 1941 UNITED STATES PATENT OFFICE izzzi'izismisriiApplication May 1, 1939, Serial No. 27l,057

8 Claims.

My invention relates to a new an useful heating device. Moreparticularly, it relates to an electrical heating apparatus forcontainers constructed of glass, metal, earthen ware, or the like.

There is a wide range of operations in which containers or flasks areutilized in the heating of liquids or liquids containing solidmaterials. As, for example, such vessels may be employed as digesters,as kettles for fractionating columns, as kettles in which liquids arekept refluxing for long periods of time, etc.

Such containers are heated in a variety of ways, for example, by the useof oil baths heated with open flames, hot plates, electrical immersionheaters, sand baths, steam Jackets, etc. In numerous operations, inparticular where containers are used as kettles for'fractionatingcolumns, a very exactcontrol of the heat input is highly desirable, andin some cases imperative. In the absence of exact heat control, floodingand derangement of packing in the column often occurs, resulting infaulty fractionation and considerableloss of time. This is especiallytrue when the fractionation is carried out at greatly reduced pressures.Such methods mentioned as hereinbefore disclosed, do not furnish thisexact control.

Among the most serious disadvantages in certain of the methodspreviously employed for heating flasks, are the possibility of fires,and other hazards. This is particularly true of oil baths which areheated with open gas flames. Costly fires, and even loss of life havemany times occurred when oil baths are heated with open names. In many,laboratories, and other establishments. large volumes of volatile andinflammable solvents are used, and the presence. of an open flame insuch places is therefore highly objectionable. v

I have now discovered that the above-mom tioned difilcuities may beovercome by utilizing my new electrical heating device, some of thedetails of which I have already described in an article entitled:Improved Method of Heat In put Control in Glass Fractionatlng Columns,"-

which appeared in the Analytical edition of Industrial and EngineeringChemistry, vol. 30, page 531, September 1938.

My invention consists broadly of an electrical heatingdevice in whichfabrics woven of materials, such as glass or asbestos fibers, areemployed in a plurality of layers, in combination with suitable heatingelements, in such a manner as to permit of exact heat input control. Ifdesirable, a suitable insulating material, such as rock wool, glasswool, asbestos fibers, or the like, may be placed between the heatingelements and one or more 01 the outer layers of fabric.

My invention may be more particularly de- 5 scribed by referring to theaccompanying drawing, in which a glass flask I, such as that employed asa kettle for fractionating columns, is covered with a mantle 2 of afireproof fabric woven of asbestos or glass fibers. The fabric may befitted closely to the flask by cutting a suitable pattern and sewing iton to the flask. Preferably the fabric should be woven in the form of ahemispherical mantle which covers approximately half the surfaceof theflask I. Two such hemispherical mantles cover, the entire surface of theflask except for openings cut into the mantle where desired. This firstmantle 2, in the accompanying drawing, protects the flask from directcontact with the electrical heating elements. Over this first mantle(layer or covering) another mantle 3 is fitted. The mantle 3 is alsowoven of asbestos or glass fibers, wherein electrical heating elements,having terminals 4, may be woven or' sewn into the fabric Der se,. ordisposed between the fabric layers in any convenient manner. Over themantle 3, suitable insulating material 5 is fitted. This insulatingmaterial may consist of glass wool, asbestos fibers, rock wool, or othersuitable material. Over the insulating material is fitted an externalmantle 6 of fabric also woven of asbestos, glass fibers, or the like. Alight well I is fitted into the flask by means of a seal, or by meansof,a ground glass joint, by which observations within the flask can bemade, when desired, by the use of a suitable electrical lighting device.The electric light employed for this purpose is mounted on a suitablerod, which is calibrated in such a manner so that it is possible todetermine the volume of the contents of the flask at any desirableinterval. The whole assembly of mantles, heating elements, andinsulating materials is preferably constructed in the form of twohemispherical members, as shown in the drawing. The hemisphericalsegments may be held togather on the flask by any convenientinterlocking means such as by means of sewing, by hooks and eyes, clampsor the like. However,'I have found it advantageous to employ a Zipperfor this purpose, said Zipper encircling the assembly at the boundary 8of the two hemispherical mem bers. If the flask is accidentally broken,the heating device can then be quickly removed and transferred toanother fiask. The heating current may be accurately controlled byvariable transformers (varlaca), or by an external resistance.

It may be desirabieto heat only a portion ofthe surface of the flask, asin the case of liquid phase chlorinations, at or near boilingtemperatures, and which require light as a catalyst; or in instanceswhere a refluxing operation is necessary, it is preferred to employ onlythe lower member of the heating device, since conditions of this typefavor a condensation of the liquid,

short period of time in a removable container.v

Likewise, my invention may be'employed in heating containers of anyshape, provided the design of the heating device utilized fits thecontours of the container.

Flasks heated in this manner are seldom broken because of the thickprotective covering offered by the heating device. Fractionating columns:whose kettles are heated in this manner may he controlled so exactlythat they will operate for hours, or even days, with but very littleattention.

Having now described my invention, what I claim is:

1. In a heating device, the combination comprising two hollowhemispherical members comprising a plurality of fireproof fabric layerscontaining electrical heating elements in and between at least one ofsaid layers, and an interlocking means for joining the two said hollowhemispherical members.

2. In a heating device, the combination comprising two hollowhemispherical members comprising a plurality of fireproof fabric iayerscontaining electrical heating elements in and between at least one ofsaid layers, and a Zipper device by which two said hollow hemisphericalmembers are held in combination.

3. A heating device adapted to be detachably fitted to a glass vesselfor heating the same, comprising a plurality of layers of flexible wovenfireproof fabric formed into a pliable, resilient structure adapted toprotect said vessel from mechanical shock and shaped to conform closelyto the exterior of said vessel and to cover the bottom and at least aportion of the side walls thereof, and an electrical heating elementinterposed between layers of said fireproof fabric and afiixed to thewoven structure of one of said layers in spaced and non-shortingrelationship. 4. A heating device adapted to be detachably fitted to aglass vessel for heating the same, com- I non-shorting relationship.

5. A heating device adapted to be detachably fitted to a substantiallyspherical glass flask for heating the same, comprising a plurality oflayers of flexible woven fireproof fabric formed into a pliable,resilient structure forming a'substantially spherical segment adapted toconform closely to the exterior of the lower portion of said flask, andan electrical heating element interposed between layers of saidfireproof fabric and affixed to the woven structure of one of saidlayers in spaced and non-shorting relationship.

6. A heating device adapted to be detachably fitted to a substantiallyspherical glass flask for heating the same,- comprising a plurality oflayers of flexible woven glass fabric formed into a pliable, resilientstructure forming a substantially spherical segment adapted to conformclosely to the exterior of the lower portion of said flask, and anelectrical resistance wire heating element interlocked in the wovenstructure of an intermediate layer of said glass fabric in spaced andnon-shorting relationship.

'7. A heating device adapted to be detachably fitted to a substantiallyspherical glass flask for heating the same, comprising an inner layer offlexible woven fireproof fabric, an adjacent layer of flexible wovenfireproof fabric having attached thereto, in spaced and non-shortingrelationship, an electrical heating element, and an outer layer offlexible woven fireproof fabric, the said layers being formed into asubstantially hemispherical, pliable, resilient structure adapted toconform closely to the lower half of said flask, and to protect the samefrom mechanical shock.

8. A heating device adapted to be detachably fitted to a substantiallyspherical glass flask for heating the same, comprising an inner layer offlexible woven glass fabric, an adjacent layer of flexible woven glassfabric having interlocked in its woven structure, in spaced andnon-shorting relationship, an electrical resistance wire heatingelement, and an outer layer of flexible woven fireproof fabric, the saidlayers being formed into a substantially hemispherical, pliable,resilient structure adapted to conform closely to the lower half of saidflask, and to protect the same from mechanical shock.

GLEN H. MOREY.

